1. Field of the Invention
The present invention relates to a printed circuit board for an optical waveguide and a method of manufacturing the same, and, more particularly, to a printed circuit board which can be efficiently used to fabricate an optical waveguide using a relatively small amount of a clad material and a core material by forming a lower clad layer only in a through-hole of an insulation layer and by applying a core material only on the inner surface of the through-hole and then conducting a patterning process to form a core part, and a method of manufacturing the same.
2. Description of the Related Art
Recently, the demand for an optical substrate including optical wire enabling electrical signals and optical signals to be transmitted to mobile or network equipment has increased.
Generally, an optical wire is made of a polymer having low optical transmittance, and includes a square core part having a x-width of about 50 μm and a y-width of about 50 μm through which signals are propagated, and a clad part covering the square core part. The square core part is generally fabricated through a photo-etching process.
In relation to this, a conventional method of manufacturing a printed circuit board for an optical waveguide will be described as follows with reference to FIGS. 1A to 1C.
First, a lower clad layer 13 and a core layer 14 are sequentially formed on a polyimide layer 12 of a flexible substrate including copper foil 11 and the polyimide layer 12 (see FIG. 1A).
Next, the core layer 14 is patterned through a general photo-etching process to form core parts 14a (see FIG. 1B).
Finally, an upper clad layer 15 is formed on the lower clad layer 13 including the core parts 14a formed thereon, thus producing a printed circuit board for an optical waveguide (see FIG. 1C).
However, the conventional method of manufacturing a printed circuit board for an optical waveguide is problematic in that, since the core layer 14 is formed by applying a core material on the entire work area of the substrate and then the core layer 14 is patterned through an exposure/development process to form the core parts 14a, a very large amount of the core material is unnecessarily removed compared to the amount of actually required core parts 14a, and thus the loss of material cost is increased.
Further, the conventional method is problematic in that, since the lower and upper clad layers 13 and 15 are formed throughout the substrate although it is sufficient that they cover the core parts 14a to such a degree that the core parts 14a can easily transmit optical signals, a clad material is excessively used unnecessarily.
Therefore, considering that an optical wire is expensive, it is keenly required to manufacture an optical substrate through an economical and efficient method.